Madwa is a tall and very slender, even skinny, woman. She has pale skin, light-gray (almost white hair) and dark eyes. While appearing to be of rather advanced age, she seems quite physically and mentally fit. She wears the same purple and black colors favored by other Smoke Knights; but, unlike the others we have seen so far, has a black diamond-shaped mark on her forehead. This may be shared by all members of her group and it may be permanent, given that the forehead of an incinerated corpse nearby during her first appearance in the comic (whom she refers to as Bartleby and presumably a member of her group) displays this mark.
Madwa was kicked out of the Smoke Knights by Grandmother, due to her continued loyalty to Lucrezia/the Other after all the Knights were ordered to cut their ties to Lucrezia or anyone loyal to her. Madwa and her group had been slavishly loyal to Lucrezia, however, and refused Grandmother's ultimatum, staying allied with her and the Geisterdamen.
Agatha first encounters her in the catacombs under Paris, where they are both searching for Prende's Chronometric Lantern. Madwa soon shows her advanced Smoke Knight skills, evading a gas attack, flitting about unseen, shaking off a serious electrical jolt, escaping the grasp of Prende herself and finally making off with the Lantern, albeit in a damaged state. In the process she appears to have one of her hands seriously burned or withered in some fashion by the revived Storm King.
She is next reported to be taking a submarine to England with Zardeliv in tow, but Agatha and Co. are able to get there first via airship and are waiting when the sub comes crashing into Londinium's undersea docks. The sub is forced open to reveal everyone inside dead via gas-poisoning, including (supposedly, theoretically) Madwa and Zardeliv, There is no sign of the Lantern.